I am trying to study cell proliferation using BrdU immunofluorescence. I use control cells which I know are proliferating obtaining no results. I think it is because of BrdU concentration (I have read that I can only use 10microM). Have anybody try with higher concentrations?

Are the cells confluent? If they're confluent or close to it, they won't be proliferating and the BrdU assay probably won't work. Have you tried lowering the number of cells plated? Also maybe try increasing the amount of anti-BrdU antibody used and double checking that your reagents are still good.